Retinal image motion provides one source of the sensory feedback used in the reflexive control of body sways. This is necessary for achieving a stable body orientation. Details of the motion feedback are dependent, among other factors, on voluntary head or eye movements and on refractive conditions of the eye. Hypotheses to be tested here are: a) The retinal image motion per se produced by a voluntary eye movement can, if simulated in a stationary eye, disrupt body sway control. (Pilot results confirm this). b) The quantitative gain relationship between eye movement and retinal image motion may have an optimal value to prevent spatial disorientation. The gain relationship referred to in b) is relevant to refractive states involving inhomogeneous lateral magnification. Patients who initially experience this frequently complain of disorientation, until they "adapt." Findings here are expected to shed light on the adaptation to spectacle lenses observed clinically.